Electric control devices with mechanical interlock

ABSTRACT

An improved electric control combination characterized by two similar contactors mounted in a side-by-side relationship with a mechanical interlock interposed therebetween which interlock limits the contactors to alternate operation. The interlock includes a cross beam and a pair of links, the links being pivotally mounted on the cross beam and the cross beam being reciprocally moveable between first and second positions.

United States Patent 1 Owen [541 ELECTRIC CONTROL DEVICES WITH v MECHANICAL INTERLOCK Edward A. Owen, Qakmont, Pa.

Westinghouse Electric Corporation, Pittsburgh, Pa.

Filed: Mar. 28, 1972 Appl. No.: 233,95;

Inventor:

Assignee 0.8. CI. ..3 35/l60, 200/50 C Int. Cl. ..H0lh 9/26 Field of Search ..335/l60, 161;

200/50 C, l7, 18; 74/483 PB; 192/131 [56] References Cited UNlTEl) STATES PATENTS 3,391,257 7/l9 68 Frank; ..2oo/s0-c 1 3,736,538 1 May 29, 1973 2,749,414 6/1956 Haas", ..l92/l3l 2,359,606 10/1944 Ballou. ..'..335/l6 0 2,604,796 7/l952 Freese ..335/l60 Primary Examiner-Harold Broome Attorney-A. T. Stratton. Clement L. McHale and L. P.Johns 57} ABSTRACT An improved electric control combination characterized by two similar contactors mounted in a sideby-side relationship with a mechanical interlock interposed therebetween which interlock limits the contactors to alternate operation. The interlock includes a cross beam and a, pair of links, the links being pivotally mounted on the cross beam and the cross beam being reciprocally moveable between" first and second positions.

10 Claims, 19 Drawing Figures PATENTEDMAY 29 1915 sum 2 OF 7 'sHEE-IuuH PATENTED MAY 29 I975 PAIENIEumzslsza v sum 5 0F 7 6'0 3'0 I00 TRgEL OF THE OTHER END m 0 mm 30% m5 m mzomodz THE CROSS BEAM ELECTRIC CONTROL DEVICES WITH MECHANICAL INTERLOCK CROSS-REFERENCES TO RELATED APPLICATION This application is related to the invention disclosed in the application of Kurt A. Grunert et al Ser. No; 238,839, filed Mar. 28, 1972.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an electric control system comprising at least two control devices and a mechanical interlock therebetween.

, 2. Description of the Prior Art Mechanical interlocks have been used between circuit interrupters such as contactors to prevent both both circuit breakers from being in closed circuit positions simultaneously. Such interlocks normally employ a pivoted beam or teeter-totter means to assure that both circuit breakers are not closed simultaneously. Due to tolerances, minimum open gap, and overtravel requirements, the pivoted beam mechanism provides inadequate motions because it gives a one-toone relationship between the motions. Although the relative motion characteristics can be varied by changing the lengths of the various pivot arms and pivot spacings, multiple operation is not completely prevented. For that reason, there is a need for simple reliable means to perform the function of preventing one circuit breaker from moving to the closed. position when another breaker is in that position as well as to prevent one circuit breaker from momentarily arriving at the closed position before the other breaker leaves that position. Associated with the foregoing has been a problem in prior known mechanical interlocks of binding between the movable parts which has resulted in less than satisfactory operation of the interlocks.

SUMMARY OF THE INVENTION two control devices and an interlock therebetween,

each control device comprising a stationary contact structure, a movable contact structure and electromagnetic means for actuating the movable contact structure with respect to the stationary contact structure between open and closed positions of contacts comprised in both structures, the interlock between the control devices comprising linkage means including a cross beam and a pair of links, the interlock also comprising a housing including a base which base comprises part of the linkage means, the cross beam being spaced above the base, the lower end of each link being pivotally mounted on the base at spaced locations from each other, the upper end of each link being pivotally mounted on the cross beam at locations less than the spacing between the lower ends of the links, an actuator for each end of the cross beam, the actuators extending through openings in the housing and being disposed in the path of movement of the corresponding movable contact structure for each control device, whereby the cross beam is reciprocably movable between first and second positions and has one end portion cooperable with one actuator for holding the movable contact structure of the other control device in its unoperated position and having another end portion cooperable with the movable contact structure of the other control device for holding the movable contact structure of said one control device in an unoperated position in said second position of the cross beam.

The advantage of the electric control system of this invention is the provision of a mechanical interlock that limits travel of two sets of electrical contacts so as to prevent (1) simultaneous closure of both contact sets, and (2) arcing of either or both sets. Finally, it is desirable for the interlock mechanism to aid in opening up a just-released contact set when closing the other contact set.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of an electric control device constructed in accordance with principles of this invention;

FIG. 2A is an exploded isometric view of the front part of the control device seen in FIG. 1;

FIG. 2B is an exploded isometric view of the back part of the control device seen in. FIG. 1;

FIG. 3 is an isometric view of the arc-hood device seen in FIGS. 1 and 2A, with the device being'turned over from the position in which it'appears in FIGS. 1 and 2A;

FIG. 4 is a top plan in FIG. 1;

FIG. 5 is a plan view with the arc-hood removed, of the control device of FIG. 4;

FIG. 6 is a bottom plan view of the front panel (the part seen in FIG. 2A) of the control device of FIG. 1;

FIG. 7 is a sectional view taken generally along the line VII-VII of FIG. 4;

FIG. 8 is a sectional view taken generally along the line VIII-VIII of FIG. 7;

FIG. 9 is a side elevational view of an auxiliary contact device;

FIG. 10 is a left side elevational view of the auxiliary contact device seen in FIG. 9;

FIG. 11 is a sectional view taken line XI-XI of FIG. 10;

FIG. 12 is a sectional view taken generally along the line XIl-XII of FIG. 8 of two identical control devices, of the type herein described, mounted in a substantially abutting side-by-side relationship with four auxiliary view of the control device seen generally along the contact devices'and a mechanical interlock shown in plan view in this figure; 7

FIG. 13 is an isometric view of the insulating contact carrier seen in FIGS. 2A and 7;

FIG. 14 is a side sectional view of the mechanical interlock shown in FIG. 12;

FIGS. l5, l6, and 17 are side sectional views of another embodiment of the interlock seen in FIG. 12; and

FIG. 18 is a graph showing the relationship-of percentages of travel two types of interlocks.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, there is shown in FIG. 1, an electric control device or contactor 5 comprising a metallic base plate 7 and a contactor structure 9. The contactor structure 9 comprises a back part 11 (FIG. 2B) and a front part 13 (FIG. 2A) which parts are connected together by means of two screws 15 (only one screw being shown in FIG. 2A). The contactor structure 9 is secured to the base plate 7 by means of two screws 17 (only one screw 17 being shown in FIG. 2B) which connect the back part 11 to the base plate 7 in a manner to be hereinafter specifically described.

As can be seen in FIG. 2B, the back part 11 of the contactor structure 9 comprises a back insulating housing part 19, a generally U-shaped magnetic core member 21, a coil structure 23, two generally Z-shaped supports 25 and two spring members 27 disposed over the supports 25.

As is best seen in FIGS. 28, 7 and 8, the mounting plate 7 comprises a sheet metal plate member bent over at the four sides thereof to form four leg portions 29 that support the generally rectangular upper supporting plate part 31. The upper plate part 31 comprises a generally planar supporting surface having a hump 33 formed therein, which, as can be seen in FIGS. 7 and 8, is a generally convex surface that serves to support the core member 21 in a manner to be hereinafter specifically described. A shock-absorbing resilient elastomeric or rubber member 35 is disposed on the plate 7 over the hump 33. A member 35 comprising a neoprene rubber member has been successfully tested in a control device of the. type herein described.

The coil structure 23 comprises a conducting coil 37 (FIGS. 7 and 8) encapsulated in an insulating shell 39. Two slab-type terminal conductors 41 (FIG. 2B) extend from the insulating shell 39 to enable connection of the coil 37 in an electric circuit. As can be seen in FIGS. 2B, 7 and 8, the coil structure 23 has two openings therein which receive the two legs of the generally U-shaped magnetic core member 21. The magnetic core member 21 comprises a plurality of laminations forming two leg parts 43 (FIG. 8) that extend upward to provide two pole faces 45 having shading coils 46 supported therein. The core member 21 also comprises two extensions 47 (FIG. 8). During assembly of the contactor 5, the shock absorbing pad 35 (FIG. 2B) is first placed on the supporting part 31 of the plate 7 just over the hump 33. The magnetic core member 21 is then set down on top of the pad 35. Thereafter, the insulating housing part 19 is placed down over the core 21 with the core protruding through an opening in the housing part 19 and with two ledges 49 (FIG. 8) being disposed just over the extensions 47 of the core 21. The

' Z-shaped supports 27 are then placed in position and the screws 17 are passed up from the bottom of the plate 7 through suitable openings in the insulating housing part 19 and threaded into tapped openings in the lower legs of the supports 25 in the manner disclosed in FIG. 7. Thus, the screws 17 draw the supports 25 and insulating housing part 19 toward the plate 7.

This movement, because of the engagement of thehood device 59. The generally U-shaped armature 57 has a separate pole face 58 (FIG. 7) at the outer end of each of the two leg portions thereof. As is best seen in FIGS. 2A and 5, four pairs of conducting straps 61 are secured to the insulating housing top part 53 by means of screws 63. A separate terminal plate 65 (FIGS. 1 and 2A; not shown in FIGS. 4, 5 and 7 for the purpose of clarity) is connected to the outer end of each of the conducting straps 65 by means of a terminal screw 67. A stationary contact 60 (FIGS. 2A and 7) is brazed or otherwise suitably secured to the inner end of each of the conducting straps 61. A separate bridging contact member 71 is provided to bridge each pair of separated stationary contacts 69. As can be seen in FIG. 7, each of the bridging contact members 71 comprises a conductor 73 and two stationary contacts 75 secured to opposite ends of the conductor 73. As is best seen in FIG. 2A, the insulating contact carrier 55 has four window openings therein. Each of the bridging contact members 71 is supported on the contact carrier 55 in a separate window openings. In each of the openings a separate compression spring 77 biases a spring support 79 against the associated bridging contact member 71 to retain the member 71 in place and to provide for resilient contact engagement. As can be seen in FIG. 7, the insulating contact carrier 55 has an opening therein and a generally U-shaped laminated magnetic armature 57 is supported in the opening on the contact carrier 55 by means of a supporting pin 81 that passes through a suitable opening in the right portionof the U-shaped armature 57 and is supported on ledges on a surface of the insulating contact carrier 55. A generally resilient shock absorbing pad 82 is mounted between the armature 57 and contact carrier 55. During assembly of the upper or front part 13 of the contact structure 9, the insulating contact carrier 55 and the magnetic armature 57 are moved up through an opening from the bottom of the insulating housing part 53 and, thereafter, the bridging contact members 71 are mounted in position in the window openings of the contact carrier 55 to thereby secure the insulating contact carrier 55 and armature 57 along with the bridging contact members 71 in position on the upper housing part 53.'As can be seen in FIG. 3, the arc-hood device is a molded insulating member having four arc chambers 85 formed therein to extinguish the arcs drawn between the separating contacts of the four poles of the contactor 5. The insulating contact carrier 55 is provided with two upper extensions 87 that protrude through two openings 89 (FIG. 2A) in the archood device 59 to provide alignment of the contact carrier 55. The arc-hood device 59 is secured to theupper part 53 of the insulating housing by means of two screws 89 (FIGS. 1 and 2A) that arescrewed into tapped openings 91 (FIG. 2A) in the upper housing part 53. The front or upper part 13 (FIG. 2A) is secured to the back or'lower part 11 (FIG. 2B) of the contactor structure 9 by means of two screws 15, only one of which is shown in FIGS. 2A and 7. Each of the two screws 15 is threaded into an upper tapped opening in a different one of the two supports 25. The two screws 15 connectthe top part (FIG. 2A with the bottom part (11 FIG. 2B) of the contactor structure 9. The two springs 27 engage the contact carrier 55 at 90 (FIG. 6) to bias the contact carrier 55, armature 57, and bridging contact members 71 to the upper unattracted position seen in FIG. 7. Tubular conducting socket members 91 (FIGS. 2A, 6 and 8) are suitably supported at opposite sides of the insulating housing part 53 to cooperate with the two stab members 41 (FIG. 2B). A separate terminal screw 93 (FIG. 2A) is connected to each of the tubular socket members 91 to enable connection of the tubular sockets 91 in an electric circuit. When the top part 13 (FIG. 2A) is com nected to the bottom part 11 (FIG. 2B), the two conducting stabs 41 that are electrically connected to the energizing coil 37 (FIG. 7) are forced into the openings of the tubular conducting sockets 91 to connect the terminal 93 to the coil 37 whereby when conductors (not shown) are connected to the terminals 93 the coil 37 will be connected in the electric circuit of the conductors.

As can be seen in FIG. 5, the contactor that is herein disclosed is a four-pole contactor with four separate controlled conducting paths extending lengthwise through the contactor. The contactor is herein described as having a length and width; but it is to be clearly understood that the word length is not necessarily limited to a dimension that is longer or as long as the width of the contactor. As can be seen in FIG. 5, the conductors 61 are shaped to provide that the plurality of conducting paths converge from each of the two opposjte endsthereof toward the center to thereby provide additional space at each of the two opposite sides of the plurality of conducting paths for the terminals 93. Additional openings 95 are provided in the housing part 53 to receive additional conducting sockets 91 and terminal screws 93 when a dual voltage coil is utilized in the contactor. As is seen in FIGS. 1 and 2A,'each of the four conducting paths is separated and electrically insulated from the adjacent paths by means of insulating barriers that are molded integral with the housing part 53.

With the provision of the conducting paths converging from the terminals toward the bridging contact members, the terminals can be separated to provide adequate electrical clearance between adjacent terminals and adjacent wires that would be connected to the terminals, and the contactor is still provided with four conducting paths across the top thereof along with room at each of the two opposite sides of the four conducting paths for the coil terminals 91, 93.

Although the relay contactor that is herein described provides four normally open contact positions, it can be understood that the shape and form of these contacts can be changed in order to provide normally closed operation in a manner that is well known in the contactor art. It is also to be understood that the contactor can be constructed with more or less than four poles.

Referring to FIG. 7, the contactor 5 is shown therein with the contact carrier and armature biased to the upper unattracted position by means of the springs 27. When the contact carrier 55 is in this position, the four bridging contact members 71 are in the upper position separated from the stationary contacts 69 so thatthe four poles of the contactor are normally opened. Upon energization of the coil 37, the armature 57 is pulled,

against the bias of the springs 27, into engagement with the generally U-shaped magnetic core member 21. This movement is limited by engagement of the two pole face 58 of the generally U-shaped armature 57 with the adjacent two pole faces 45 of the generally U-shaped core member 21. During this movement, the springs 27 are compressed and charged and the four bridging contact members 71 are moved down into engagement with the contacts 69 whereby each of the bridging contact members 71 closes a circuit between the associ# ated stationary contacts 69. Each of the springs 77 is 6 compressed slightly during the closing operation to provide contact pressure between the closed contacts. With the armature 57 in engagement with the magnet yoke 21, and with the contact carrier 55 in the lowerposition charging the springs 27, when the coil 37 is deenergized, the charged springs 27 will expand moving the insulating contact carrier 55 upward to the position seen in FIG. 7 to move the armature 57 and the four bridging contact members 71 upward to the unattracted position. This movement is limited by engagement of shoulder portions 96 (FIG. 7) on the insulating contact carrier with ledge portions 98 on the insulating housing part 53. The contactor can then be again operated in the same manner by energization of the coil 37.

During each closing operation of the contactor 5, the shock absorbing pads 35 and 82 reduce the shock of the impact between the armature 57 and core 21. The core 21, being disposed over the hump 33 of the mounting plate 7, can move universally to the limited extent in any direction to provide automatic alignment of the pole faces 45 of the core 21 with the pole faces 48 of the armature 57. This cushioning dampens shocks from armature impacts not only in its own contactor assembly but also in adjacent units to thereby reduce contact bounce and wear between the contacts and also between the pole faces of the magnet yoke and armature. The self-aligning feature comprising the core mounting means saves wear on the parts and it also contributes to provide for a quieter operation of the contactor. Moreover, with the provision of a metallic mounting plate 7 comprising a raised supporting part 31 and four feet 29, the raised supporting part 31 will flex slightly during each closing operation and some of the energy of the impact of the armature against the yoke will be absorbed due to internal strain energy in the mounting plate. Thus, the particular mounting arrangement of the yoke 21 serves to aid in reducing: contact bounce and contact wear, magnet yokearmature pole face wear, fatigue in the structuralmembers, and the noise level of the operation of the contactor.

There is shown in FIGS. 9-11, three views of an electrical interlock or auxiliary contact device 101. The auxiliary contact device 101 comprises an insulating housing 103 having two upper conductors 105 supported therein and two lower conductors 107 supported therein. A separate stationary contact 109 (FIG. 11) is welded or otherwise secured to each of the conductors 105 and a separate stationary contact 111 is welded or otherwise suitably secured to the conductors 107. The conductors 105 extendout through openings at the side of the insulating housing 103 and a separate terminal screw 113 is supported at the outer end of each of these conductors to enable connection of the contacts 109 in an electric circuit. The conductors 107 extend out through the side of the insulating housing and a separate terminal screw 115 is provided at the outer end of each of these conductors to enable connection of the contacts 111 in an electric circuit. An insulating operating member and contact 117 is mounted for reciprocal rectilinear vertical movement in the insulating housing 103. The member 117 is provided with a window opening therein and two bridging contact members 119 and 121 are supported in the opening by means of a spring 123. The bridging member 119comprises a conducting member 125 and two contacts 127 or otherwise secured to the opposite ends of the members 125. The bridging contact members 121 comprises a conductor 131 and two contacts 133 welded or otherwise secured to the opposite ends of the member 131. An operating spring 117 biases the member 117 and therefore the two bridging contact members 119 and 121 to the upper position shown in FIG. 1 l. A lower resilient spring steel clip member 139 is secured to the housing 103 and an upper resilient spring steel clip member 141 is secured to the upper part of the housing 103. The auxiliary contact device 101 is operated by depression of the member 117 which movement charges the operating spring 137. This downward (FIG. 11) movement of the member 117 moves the upper bridging contact member 119 from the normally closed to an open position. This movement of the member 117 also moves the lower bridging in FIG. 1 1 wherein the upper bridging contact member 119 is in the upper normally closed position and the lower bridging contact member 121 is in the lower normally open position. It is to be understood that these contacts can also be mounted to provide two normally open sets or two normally closed sets of contacts in a manner well known in the art.

Referring to FIG. 1, it will be noted that the insulating housing part 19, the insulating cover 39 of the coil structure 23 and the'insulating housing part 53 mate and cooperate, along with the insulating arc-hood device 59 to form the insulating housing structure of the contactor structure 9. The insulating parts 19, 39 and 53 are formed to provide four cavities, one at each of the back four corners of the contactor structure. The cavities are identified as C C C and C The cavity C.,, which cannot be seen in FIG. 1, is seen in FIG. 12. Each of the four cavities is either identical or symmetrically identical to each of the three other of the four cavities. The insulating housing part 53 overhangs the four cavities C C C and C, at the four corners 0 0 0 and 0 thereof (FIGS. 1 and 6) respectively. The four corners P P P and P, (FIGS. 1, 2B and 12) of the mounting plate 7 serve as the four bases of the cavities C C C and C, respectively. The mounting plate,

at each of the four corners thereof, is formed with a depression 147 stamped therein, and two openings 149 that are provided one at each of the two opposite edges of each corner. Referring to FIG. 12, there is shown therein, in section, one of the control devices 5 and part of another of the control devices 5, which devices are mounted in a substantially abutting side-by-side relationship. As can be seen in FIG. 12, the contactor 5 (on the right) is provided with an electric interlock 101 in the cavity C,, an open cavity at C one-half of a mechanical interlock indicated generally at 153 in the cavity C and an open cavity C Two auxiliary contact devices 101 are disposed outside of the cavity C, and dotand-dash lines are drawn into the cavity C, in order to indicate that either of these electrical control devices could be mounted in the cavity C, by means of a rectilinear movemet into the mounted position. Thus, it is to be noted that an electrical interlock can be mounted in any of the four cavities of the contactor in either of the'two positions indicated at the cavity C in FIG. 12. When one of the auxiliary contact devices 101 is moved into the mounted position in he associated cavity, the lower spring clip 139 (FIGS. 9-11) passes through the associated opening 149 and the clip is additionally spring charged when the end part thereof engages the lower depression 147 to provide frictional support. The upper spring 141 engages in an associated notch 155 (FIGS. 1 and 6) and is spring charged against the overhang in the notch 155 to provide spring pressure whereby the springs 139, 141 of the auxiliary contact device maintain the contact device 101 in the mounted position in the cavity. Referring to FIG. 6, it will be noted that the insulating contact carrier 55 is provided with four comers A A A and A, molded as integral parts of the contact carrier. Each of the corners A A A and A, serves as an actuating part moving in the associated cavity rectilinearly in a vertical (FIGS. 7 and 8) direction with the insulating contact carrier to-thereby engage and actuate the operating member 117 of an auxiliary contact device if the auxiliary contact device is disposed in the cavity. The auxiliary contact 101 will be actuated by the associated actuating part of the contact carrier 55 in either of the two possible mounted positions (see C, of FIG. 12). It will be noted that the operating member 117 of the auxiliary contact device is wide enough so that it will be disposed in the inside corner portion of the cavity just under the actuating part of the contact carrier regardless of the direction of mounting (see C, of FIG. 12) of the rectifier contact device in the cavity. With the auxiliary contact device in position, the terminals 113 and 115 (FIG. 9) are accessible for connection of the associated contacts in an electric circuit. As can be seen in FIG. 12, when the auxiliary contact device 101 is mounted in the cavity (the auxiliary contact device being shown fully mounted in the cavity C,) the contact device 101 does not extend past the length and width dimensions of the insulating housing parts 19, 39, 53 (FIG. 1) and, since the base plate 7 serves as the base of the cavity and because the insulating member 53 overhangs the associated cavity space, it can be understood that the auxiliary contact device is disposed such that it will not take up additional space in a panelboard or control center. The auxiliary contact device 101 is readily removably mounted in position by merely being moved into the mounted position with the spring clips 139, 141 serving to retain the auxiliary contact device in position. If desired, additional attaching means such as screws could be used to secure the auxiliary contact device in position. It is to be noted that the operating member 117 of the auxiliary contact device is automatically operatively connected to the contact carrier of the container merely by means of the mounting operation.

For certain applications, it is desirable to prevent simultaneous operation of two control devices that may be mounted in a side-by-side relationship. The mechanical interlock 153 (FIG. 14) is provided for this purpose. As shown in FIG. 14, the interlock 153 comprises I a base member 157, an insulating housing structure 159, two actuators or operating members or plungers 161 supported for rectilinear vertical movement in the housing structure 159, two compression springs 163 supported to bias the operating members 161 to the upper position shown, a cross beam 165, and a pair of links 167 and 169. The lower end of the links 167 and 169 are pivotally mounted within the housing structure 159 and preferably on the base 157 by pivot pins 167a and 169a, respectively. Likewise, the upper ends of the mitting vertical motions of the ends of the cross beam into vertical motions of the contactor actuating corners A, and A The cross beam 165 reciprocates horizontally within the housing 159 and interlocks the operating members 161 so that they cannot be simultaneously depressed. If one of the members 161 (such as the left member as shown in FIG. 14) is depressed by the corner A,, the cross beam 165 will be moved to the inclined broken-line position 165a and raise the other member 161 to prevent depression of the corner A If both corners A and A are moved simultaneously, the cross beam 165 is prevented from movement and remains fixed in place. Thus, the interlock 153 provides that the operating member 161 cannot be moved to the lower operating positions at the same time.

Referring to FIG. 12, it will be noted that when the two control devices 5 are mounted in a substantially abutting side-by-side relationship, the adjacent cavities C and C of the two devices provide a common pocket into which the mechanical interlock 153 can be disposed. The interlock 153 may be removably secured to also be similarly mounted in the upper adjacent cavities C C,. It is noted in FIG. 12, that the two operating members 161 are disposed at the inside corners of the associated cavities C C, so that each of the members 161 would be disposed under the associated actuating corners A or A, of the insulating contact carrier. Thus, with the members 161 disposed under the contact carriers of the adjacent contactors, the blocking structure 165 (FIG. 14) will operate to'interlock the contact carriers, in the same manner hereinbefore described, to prevent the contacts from being operated to the actuating position at the same time. It is also to be noted that the operating members 161 are automatically operatively connected to the insulating contact carriers of the adjacent contactors merely by means of the mounting operation of the mechanical interlock.

As shown in FIG. 14, a pair of centering springs 170 are provided in the base to facilitate returning the assembly of the cross beam 165 and the links 167 and 169 to neutral position when both operating members 161 are released.

Another embodiment of the invention is shown in FIG. 15 in which similar parts are identified with similar numbers. The embodiment in FIG. 15 differs from that of FIG. 14 in that contact between the cross beam 165 and each'member 161 is provided by an additional connecting link 171 and 172, the lower ends of which are pivotally connected at pivot pins 167b and 169b, respectively. The upper ends of the links 171 and 172 are pivotally connected to the members 161 at pivotpoint 171a and 172a, respectively. The depression of either operating member 161 by a corner A: or A causes the cross beam 165 to move in the manner described above with respect to FIG. 14.

Another embodiment of the invention is shown in FIG. 16 in which similar parts are identified with similar reference numbers. The difference in the embodiment of FIG. 16 is the provision of similar arms 173 on each member 161 which arms engage opposite ends of the cross beam 165 and thereby perform the same function as the embodiments shown in FIGS. 14 and 15. Thus, depression of either member 161 by the corner A, or A causes the interlock to operate in the manner set forth above with respect to FIG. 14.

Still anotherembodiment of the invention is shown in FIG. 17 in which similar parts are identified with similar reference numbers. The several members 165, 167,

and 169 are integral portions of a single molded part' In FIG. 18, the relationship between the percent of travel of the operating members for a given movement for two types of interlocks are compared. Curve A being a straight line inclined at a 45 angle clearly indi- I cates that with the pivoted beam or teeter-totter type of mechanical interlock of the prior art one operating member moves the same distanceas the other throughout their length of travel; i.e. there is a 1: 1 relationship between them. On the other hand, as shown by curve B, with the mechanical interlock of the present invention where one operating member 161 travels a given unit of distance, the other member 161 travels a different unit of distance. For example, when one operating member 161 is initially depressed through 20 percent of its distance of travel, the other operating member travels 40 percent of its distance of travel, and when said one operating unit 161 has reached of its distance of travel, said other operating member has completed percent of its travel. Thus, the four-bar mechanical linkage of the present inventionprovides an effective means for positively opening the circuit through onepair of contacts before closing the circuit through another pair of contacts. j w

Accordingly, the device of the present invention satisfies certain problems existent in prior art devices by preventing not only the simultaneous closure of both sets of contacts but also of preventing arcing of either or both sets. Finally, the interlock mechanism of the present invention facilitates in opening up a justreleased contact set when closing the other contact set.

What is claimed is: I l

1. An electric control system comprising at least two control devices and an interlock, each control device comprising a stationary contact structure, an electromagnet including a magnet armature, a magnetic core and a coil, a movable structure movable as a unit and comprising a movable contact structure, the magnetic armature being movable relative to the core to move the movable contact structure between an operated position and an unoperated position to control an electric circuit, the interlock being between the control devices and comprising linkage means, including a base, a cross beam, and a pair of links, the cross beam being spaced above the base, the lower ends of each link being pivotally mounted on the base at spaced locations from each other, the upper end of each link being pivotally portion cooperable with the movable structure of one control device for holding the movable contact structure of the other control device in its unoperated position in said first position of said cross beam and having another endportion cooperable with the movable contact structure of the other control device for holding said movable contact structure of said one control device in unoperated position in said second position of said cross beam.

2. The electric control system of claim 1 in which the spacing between the lower ends of the links is greater than the upper ends thereof.

3. The electric control system of claim in which the longitudinal axes of the links converge upwardly.

4. The electric control system of claim 2 in which an actuator is disposed between each end of the cross beam and the corresponding movable contact structure.

5. The electric control system of claim 4 in which the actuator comprises a member movably mounted substantially vertically of each end portion of the cross beam.

6. The electric control system of claim 4 in which the actuator comprises a vertically movable plunger extending at substantially a right angle to the cross beam in the first position.

housing including the base is provided for the cross beam and the links, and in which the housing includes opening means for receiving and guiding movement of the plungers.

8. A mechanical interlock for use between two circuit interrupters of the electromagnetic type for preventing both interrupters from being closed simultaneously, the interlock comprising a housing, a cross beam, and a pair of links, the lower ends of the links being pivotally mounted within the housing, the upper ends of the links being pivotally mounted on the cross beam at spaced locations from each other, the links being unparallel to each other, and the cross beam being reciprocally movable between first and second positions and having one end portion cooperable with one circuit interrupter and the other end portion cooperable with another circuit interrupter.

9. The mechanical interlock of claim 8 in which the housing includes a base on which the lower ends of the links are pivotally mounted at spaced locations from each other.

10. The mechanical interlock of claim 9 in which the links are pivotally mounted at spaced locations from each other by a distance greater than the spacing between the pivotal mountings of the links on the cross beam. 

1. An electric control system comprising at least two control devices and an interlock, each control device comprising a stationary contact structure, an electromagnet including a magnet armature, a magnetic core and a coil, a movable structure movable as a unit and comprising a movable contact structure, the magnetic armature being movable relative to the core to move the movable contact structure between an operated position and an unoperated position to control an electric circuit, the interlock being between the control devices and comprising linkage means, including a base, a cross beam, and a pair of links, the cross beam beiNg spaced above the base, the lower ends of each link being pivotally mounted on the base at spaced locations from each other, the upper end of each link being pivotally mounted on the cross beam at locations spaced from each other, the links being unparallel to each other, and the cross beam being reciprocally movable between first and second positions and having one end portion cooperable with the movable structure of one control device for holding the movable contact structure of the other control device in its unoperated position in said first position of said cross beam and having another end portion cooperable with the movable contact structure of the other control device for holding said movable contact structure of said one control device in unoperated position in said second position of said cross beam.
 2. The electric control system of claim 1 in which the spacing between the lower ends of the links is greater than the upper ends thereof.
 3. The electric control system of claim 2 in which the longitudinal axes of the links converge upwardly.
 4. The electric control system of claim 2 in which an actuator is disposed between each end of the cross beam and the corresponding movable contact structure.
 5. The electric control system of claim 4 in which the actuator comprises a member movably mounted substantially vertically of each end portion of the cross beam.
 6. The electric control system of claim 4 in which the actuator comprises a vertically movable plunger extending at substantially a right angle to the cross beam in the first position.
 7. The electric control system of claim 6 in which a housing including the base is provided for the cross beam and the links, and in which the housing includes opening means for receiving and guiding movement of the plungers.
 8. A mechanical interlock for use between two circuit interrupters of the electromagnetic type for preventing both interrupters from being closed simultaneously, the interlock comprising a housing, a cross beam, and a pair of links, the lower ends of the links being pivotally mounted within the housing, the upper ends of the links being pivotally mounted on the cross beam at spaced locations from each other, the links being unparallel to each other, and the cross beam being reciprocally movable between first and second positions and having one end portion cooperable with one circuit interrupter and the other end portion cooperable with another circuit interrupter.
 9. The mechanical interlock of claim 8 in which the housing includes a base on which the lower ends of the links are pivotally mounted at spaced locations from each other.
 10. The mechanical interlock of claim 9 in which the links are pivotally mounted at spaced locations from each other by a distance greater than the spacing between the pivotal mountings of the links on the cross beam. 